The introduction of this article aims to provide an objective and impersonal overview of the Linux kernel bug known as DirtyCred. This recently discovered bug, similar in severity to the previously identified DirtyPipe bug, has been active for a period exceeding eight years. Designated as CVE-2022-0847 with a CVSS score of 7.8, DirtyCred affects Linux kernels starting from version 5.8. Exploiting a use-after-free issue (CVE-2022-2588), this bug facilitates the exchange of privileged credentials for unprivileged ones, enabling privilege escalation through a novel heap memory reuse technique. Differentiating itself from DirtyPipe, DirtyCred exhibits the ability to actively escape containers, displaying increased generality and potency. Defense recommendations against DirtyCred include object isolation based on type rather than privileges, segregation of privileged and unprivileged credentials, and the utilization of vmalloc to isolate objects in virtual memory. The potential impact of DirtyCred includes local privilege escalation and the ability for attackers with local privileges to crash the system.
Key Takeaways
- DirtyCred is an 8-year-old Linux kernel bug that has been described as ‚As Nasty As Dirty Pipe‘.
- It has been reported as CVE-2022-0847 with a CVSS score of 7.8 and affects Linux kernels starting from version 5.8.
- DirtyCred exploits CVE-2022-2588, a use-after-free issue, and allows for privilege escalation by swapping privileged credentials for unprivileged ones.
- Unlike DirtyPipe, DirtyCred demonstrates increased generality and potency, allowing it to escape containers actively and exploit any vulnerability with double-free capability.
Bug Description
The bug, known as DirtyCred, has been active in the Linux kernel for over 8 years and is described as being as nasty as Dirty Pipe, with a reported CVE identifier of CVE-2022-0847 and a CVSS score of 7.8. DirtyCred’s impact is significant, as it allows attackers with local privileges to crash the system and potentially escalate their privileges. In comparison with DirtyPipe, DirtyCred demonstrates increased generality and potency. Unlike DirtyPipe, DirtyCred can exploit any vulnerability with double-free capability and actively escape containers. This makes DirtyCred a more versatile and dangerous bug. To defend against DirtyCred, it is recommended to isolate objects based on type rather than privileges, keep privileged and unprivileged credentials separate, and utilize vmalloc to isolate objects in virtual memory.
Exploitation Method
Utilizing a novel technique of heap memory reuse, the exploitation method of the recently disclosed Linux kernel vulnerability allows for privilege escalation without overwriting crucial kernel data fields. This technique takes advantage of a use-after-free vulnerability, specifically CVE-2022-2588, to swap privileged credentials for unprivileged ones. Unlike previous dirty pipe attacks, this method does not rely on overwriting critical kernel data fields, which increases its generality and potency. By exploiting any vulnerability with double-free capability, it can actively escape containers, further expanding its reach. The heap memory reuse technique employed by this exploitation method demonstrates a new avenue for attackers to escalate privileges and gain unauthorized access. It is imperative for defense strategies to isolate objects based on type, keep privileged and unprivileged credentials separate, and utilize vmalloc to segregate objects in virtual memory. The impact of this exploitation method includes the potential for local privilege escalation and system crashes when exploited by attackers with local privileges.
Defense Recommendations
To enhance defense against the recently disclosed Linux kernel vulnerability, it is recommended to implement strategies such as isolating objects based on type, maintaining the separation of privileged and unprivileged credentials, and utilizing vmalloc for object segregation in virtual memory. By isolating objects based on type rather than privileges, potential attackers will face greater difficulty in exploiting the vulnerability. Additionally, keeping privileged and unprivileged credentials separate reduces the risk of unauthorized access and privilege escalation. Furthermore, utilizing vmalloc for object segregation in virtual memory provides an added layer of protection against the exploitation of the vulnerability. These defense strategies aim to mitigate the impact of the vulnerability by limiting attackers‘ ability to manipulate critical kernel data fields and reducing the potential for local privilege escalation.
Frequently Asked Questions
How long has the DirtyCred Linux kernel bug been active?
The dirtycred Linux kernel bug has been active for over 8 years. It impacts system security by allowing attackers with local privileges to crash the system and potentially escalate their privileges. Measures to mitigate its effects on Linux systems include isolating objects based on type, keeping privileged and unprivileged credentials separate, and using vmalloc to isolate objects in virtual memory.
What is the CVE score assigned to DirtyCred?
The DirtyCred bug in the Linux Kernel has a CVE score of 7.8. It impacts the security of Linux systems by allowing attackers with local privileges to crash the system and potentially escalate their privileges. Mitigation steps include isolating objects based on type, keeping privileged and unprivileged credentials separate, and using vmalloc to isolate objects in virtual memory.
Which Linux kernels are affected by DirtyCred?
The dirtycred Linux kernel bug can be mitigated by isolating objects based on type, keeping privileged and unprivileged credentials separate, and using vmalloc to isolate objects in virtual memory. There are no known exploits leveraging the dirtycred vulnerability.
What vulnerability does DirtyCred exploit?
The DirtyCred vulnerability can be mitigated by isolating objects based on type, keeping privileged and unprivileged credentials separate, and using vmalloc to isolate objects in virtual memory. There are no known cases of DirtyCred being actively exploited in the wild.
Can DirtyCred escape containers like DirtyPipe?
DirtyCred, unlike DirtyPipe, has the ability to escape containers, posing a potential risk to container security. Mitigation strategies include isolating objects based on type, separating privileged and unprivileged credentials, and using vmalloc to isolate objects in virtual memory.
